satistic math

\f\fThe distribution of the duration of human pregnancies can be described by a Normal model with a mean 268 days and standard deviation of 16 days. Suppose a certain doctor is providing medical care to 38 randomly selected women. Using CLT describe the distribution of mean duration of these women pregnancies _ . Show the empirical rule in the given graph. Ox~ N(268, 16) f(x) 0.025+ 0.02 0.015- 0.01 0.005\f\f